In Resonance Raman (RR) scattering the excitation wavelength is chosen to fall within an absorption band of the molecule under investigation. This can lead to an increased intensity of the Raman signal and an improved signal-to-noise ratio. RR has some more advantages: First, only those modes that are coupled to the electronic excitation are resonantly enhanced, which leads to a drastic reduction of the spectral complexity. Second, RR can be used to selectively investigate a specific analyte in a mixture by tuning the excitation wavelength to the absorption band of the particular analyte. A disadvantage of RR is that not only inelastically scattered light but also increased fluorescence and luminescence is observed.